This invention relates to fuel cell arrangements having a fuel cell with a preceding methanol reformer and an energy reservoir connected in parallel with the fuel cell, and to methods for controlling the energy flow of such arrangements.
Fuel cell arrangements are known in particular as low-emission power sources in the field of motor vehicles. In such arrangements methanol, contained in a tank like conventional fuel, is converted into electrical energy which drives an electric motor by a fuel cell with a methanol reformer. To produce a sufficiently high voltage, a plurality of such fuel cells are operated in series, providing a fuel cell "stack". Because a fuel cell can only be run up slowly into its operating state, an energy reservoir, for example a battery connected in parallel, serves as starting aid and as a power buffer to deal with peak power demands in the system. A disadvantage of this method is poor efficiency with low propulsion output demand i.e., a low partial load and a fully charged battery.